In one type of conventional air conditioning apparatus known in the art, drain water, generated in an indoor heat exchanger during performing of a cooling or dehumidification mode of operation, is discharged outside after sterilization. The reason for this is given as follows. Drain water condensed when cooled in the indoor heat exchanger contains various bacteria in the air. Accordingly, in the absence of a sterilization treatment, there is the possibility that when drain water is accumulated in a drain pan or drain pipe the generation of slime is caused to take place by the growth of bacteria contained in the accumulated drain water. Slime is the semi-solid substance, and the generation of slime taking place in pipes, as the drain pipe, gives rise to several drawbacks including the occurrence of water leakage by pipe clogging and the generation of unpleasant odor by decay of accumulated substances.
Concrete examples of air conditioning apparatuses of the drain water sterilization type are known. One such technique, as proposed in JP Pat. Kokai Publication No. 1992-366327 and JP Pat. Kokai Publication No. 1994-257776, uses, as an external drain pipe, a drain tube formed of an antibacterial agent-containing synthetic resin material. In accordance with the techniques as set forth in these official gazettes, drain water flowing in the drain tube is treated with the antibacterial agent contained in the synthetic resin material, thereby to prevent the accumulated drain water from becoming slimed.
Problems to be Solved
Incidentally, the problem with using a soft synthetic resin tube as a drain pipe is that the tube is liable to aged-deterioration. Especially when the tube becomes clogged to cause decay of accumulated substances, the deterioration of the tube tends to be accelerated. This may also be the problem with the case where a resinous pipe harder than the resin tube is used as an external drain pipe.
In the light of these problems with the prior art techniques, the present invention was made. Accordingly, an object of the present invention is to provide an improved water drain discharge structure for an air conditioning apparatus, thereby to prevent the generation of slime in a drain pipe and to make the drain pipe less liable to deterioration.